Phenotypic plasticity and differentiation in fitness-related traits in invasive populations of the Mediterranean forb Centaurea melitensis (Asteraceae)
asteraceae, Centaurea melitensis, Invasive species, mediterranean ecosystems
• Premise of the study: Biological invasions threaten global biodiversity, resulting in severe ecological and economic costs. Phenotypic plasticity and differentiation in fitness-related traits after introduction can contribute to increased performance in invasive populations of plants. We determined whether postintroduction evolution in trait means or in their plasticity, or inherent species-wide phenotypic plasticity has promoted invasiveness in a European annual forb. • Methods: In a common greenhouse, we compared several fitness-related traits and the phenotypic plasticity of those traits under four levels of nutrients among native and invasive populations of Centaurea melitensis. We tested 18 populations from three regions of similar mediterranean climate type: the native range (southern Spain) and two invaded ranges (California and central Chile). • Key results: Centaurea melitensis possesses overall phenotypic plasticity, which is a trait that promotes invasiveness. Invasive populations were differentiated from native plants for several trait means and their levels of phenotypic plasticity in directions that enhance competitive ability and success. Invasive plants flowered earlier and grew faster in the early stages of growth phases, important features for invasiveness. • Conclusions: Phenotypic plasticity, its evolution postinvasion, and the evolution of fitness-related trait means in invasive populations have potentially contributed to the invasion of C. melitensis in California and Chile. Along with an overall wide range of tolerance to growing conditions, C. meltiensis populations that have colonized habitats in California and Chile have undergone rapid evolution in several life history traits and the plasticities of those traits in directions that would promote invasiveness in mediterranean ecosystems.